(a) If you are using Loraserver.io ‘standalone’ without referencing external join servers, the Join EUI on devices should always be set as 00000000000.

(b) If you want to use an external join server, then you need to use different Join EUI’s that corrospond to those external join servers…

The behavior that i’m seeing today, if you use Loraserver.io by itself ( no join servers ), it will allow you to join a new device, with any Join EUI, however if you try to add a 2nd device with the same join EUI it fails. Setting all devices to 0000000 makes it work.